The expansion of cloud computing services has led to collections of servers to provide computing capacity to run various client applications. Some client-server connections use private networks. Other client-server connections use virtual private networks to exchange data over a public network as if they were directly connected by private networks. With the expansion of cloud computing services has come an expansion of datacenters to host servers. Some hosted servers are housed in multi-tenant datacenters, and share resources with other, potentially unrelated servers.
Data security and monitoring network traffic is useful in such datacenters. Data traveling between servers and client applications needs to be monitored and processed for security. Monitoring security in high-bandwidth datacenters often uses many security servers working in tandem. One problem to be addressed is how to recover from failure of one server among many.